About those WAC Bennett Dam repairs…
Back in November, I saw a notice in the paper about a BC Hydro application to the BC Utilities Commission for rip-rap repairs on the WAC Bennett Dam, and blogged about the complete and utter hypocrisy of this in relation to the Site C dam exemption: https://lailayuile.com/2015/11/30/a-river-runs-through-it-the-hypocrisy-that-is/
But as the province continued to move full steam ahead on Site C, a multi billion dollar project the government exempted from that very same process required to do repairs on the WAC Bennett dam, something just didn’t feel right. I couldn’t put my finger on it but something brought me back to take another look at those Bennett Dam repairs.
What I found was stunning in my opinion, and had received very little press other than a story in the Globe and Mail shortly before Christmas 2015-from the looks of the response to that,few had even noticed it. That lead me back to the BC Utilities Commission for another look at the documents being presented by Hydro during this regulatory review and what I found, was concerning for several reasons: https://lailayuile.com/2016/03/10/bc-hydro-responses-to-bc-utilities-commission-raises-new-questions-over-wac-bennett-dam-repairs/
The repairs were in fact extensive and long overdue.
To me it seems a very calculated risk to have allowed these conditions identified in 1998, to have gone so long- particularly when you consider the new questions raised by the utilities commission with respect to two other issues identified by the experts that had not been addressed yet.
The BC Utilities Commission had more questions for BC Hydro following that last round of questions and last week BC Hydro’s response was submitted- this is the full response package from BC Hydro that I will summarize below :
The response is long, but includes a follow up report from the same expert review panel – completed in March of this year – that identified the conditions,concerns and risks back in 2012. The panel made a number of recommendations to BC Hydro at that time including the following- it is point 5 that the BC Utilities Commission has been asking about:
Points of interest from the review panel:
Pg 19: 2.2 Rip-rap repair:
Documents have been issued which will lead to the appointment of a contractor to complete the repairs to the rock face over three seasons when water level is low. The possibility exists that stripping the rip-rap may destabilize the upper slopes and measures must be in place to address this situation
Pg33: 2.6 3D CAD & GIS models:
-The upper part of the dam is vulnerable to deformation and transverse cracking under seismic loads, in particular in the areas affected by the two sinkholes, and is also vulnerable to seismic loads at the Spillway-Embankment interface
-there is a low likelihood that given the earthquake occurs the induced cracks in the top of the dam will penetrate as deep as to full supply level where the dam is very wide. However as discussed in Section 3.4.3 the deformations and cracking are difficult to model because of the complex 3D geometry and the difficulty in modelling the pore pressure build up and loss of stiffness in the loosened fill around Sinkhole #1 under seismic loading.
– The EEP is concerned that the time for development of internal erosion from initiation to breach has been overestimated in a number of PFM, ( Performance Failure Models) and that in reality, concentrated leak erosion may develop in hours or days, not months and years as assumed. This may have important implications for how the risks are managed.
It’s all fine and dandy, but the question remains why these situations have been left so long by BC Hydro before being investigated and acted on,particularly since we know now that fracking causes earthquakes in northeastern BC.The documentation clearly shows these issues were identified as far back as 1998. And the extensive and pertinent questions of the BC Utilities Commission clearly show the value of their work in reviewing Hydro projects, which is why it remains a travesty that Site C was exempted.
The people of BC will never have the security these reviews offer as the only check and balance to BC Hydro. As Premier Clark forges ahead to get Site C past the point of no return, even contracting turbines before ground has broken, WAC Bennett dam sits waiting for repairs even as BC Hydro gets ready to borrow more money to pay the government dividends…
Kind of makes you wonder how effective & visionary the decision making at BC Hydro really is, doesn’t it? And why the Energy Minister Bill Bennett and Premier Clark would applaud such fiscal irresponsibility at all.